What Is Comfrey?
Comfrey is an amazing plant. It is known my the scientific name of Symphytum officinale it is in the genus Symphytum and in the family Boraginaceae. It is a bioaccumulator of nutrients constantly mining minerals and nutrients that other plants can’ access and makes them readily available to them. It excels at dynamic accumulation of Si, N, Mg, Ca, K & Fe. Comfrey also has good medicinal and livestock fodder qualities as well.
How many kinds are there?
There are 34 different kinds of Symphytum. There are 3 common species and lots that are more or less unknown varieties. The 3 main kinds are Symphytum Officinale or True Comfrey, Bocking 4 (Russian) Comfrey, and Bocking 14 (Russian) Comfrey. Russian comfrey (Symphytum × uplandicum) is a cross or hybrid of True Comfrey (Symphytum officinale) and Rough Comfrey (Symphytum asperum).
Comparing 3 Common Species
True comfrey is a fertile variety, it can be spread by seed. It is typically a bit smaller than the other 2 species. It also has a lower concentration of alkaloids than the hybrid varieties.
Bocking 4 Comfrey is a hybrid variety. It can only be spread by root cutting and splitting. Its leaves are smaller and rounder leaves and thicker stalks than bocking 14. Its roots also run deeper which makes this species more drought tolerant. Livestock sometimes will prefer bocking 4 over bocking 14. This would make 4 be preferable over 14 for fodder but all 3 varieties will work well.
Bocking 14 Comfrey is also a hybrid variety. Like bocking 4 it can not be propigated by seed and relies on cutting. The leaves of 14 are large narrow leaves that come to more of a point than 4. Its stalks are also thinner than bocking 4. The large leaves and thin stalks help bocking 14 to breakdown and release their nutruents faster. This makes 14 the choice for most gardeners and permaculturist.
What does Bocking mean?
The varieties known as Bocking 4 and Bocking 14 are results of the work in the 1950s by Lawrence D. Hills. He wanted a name that would not be changed when translated into other languages. This led him to choose Bocking the name of the village in Suffox, England the home of his research facility. Lawrence D. Wells is the foremost researcher of comfrey. Well know for his book Comfrey: Past, Present and Future
Uses For Comfrey
There are lots of uses for comfrey. It makes for a great livestock fodder. It seems to work well for cows, pigs, rabbits, goats, sheep, and poultry. The risks from the alkaloids is real and it should not be fed as though it was hay. It is great though as a supplement at around 5-10%. Lawrence D. Wells did a lot of research into using it as a feed supplement. By using as a fodder for livestock not only are they benefiting from the minerals and nutrients mined but there is also 26-35% protein. No other perennial crop can provide protein levels like that. When feeding to egg production poultry darker egg yolks are another quality you can expect.
As a fertilizer dried leaves can be expected to yield approximately an NPK ratio of N1.8 P.5 K5.3 . While these numbers may sound low when compared to conventional chemical fertilizers it is above average when compared to natural manures. It is exceptionally high in potassium at 5.3%. This means it is a great addition at the flowering and production stage. The high potassium levels also lend it to being good for starting root crops such as potatoes and sweet potatoes. Dynamic accumulation of trace minerals Si, N, Mg, Ca, K & Fe is yet another benefit. The nutrients and trace minerals are readily bio-available for the other plants to use unlike common chemical fertilizers. Soil tests show that nutrients increase in the presence of comfrey. Which makes it a great companion plant. Another use is as a compost activator and addition to your compost to boost the nutrient levels in your compost. It is great at mining silica (Si) if you grow squash, make sure to plant some nearby as silica is a naturally repels squash bugs.
Medicinally the plant has many uses. While being used for centuries internally the plant contains alkaloids which can be damaging to the liver so internal use is now discouraged. The concentrations of these alkaloids are highest in the roots, also they are higher in the hybrids as compared to the true species. Improvements are very common when used to treat bruises, sprains, fractured bones, minor cuts and skin irritations. It is also thought to have bone and tooth growing capabilities in children. Allantoin levels in the plant are very high, these molecules promote cell growth while reducing inflamation.
How to care for
Comfrey is a very durable plant, especially once established. Establishment is quite easy. A good amount of indirect sunlight and water will have your plants growing like crazy. Once established it is pretty drought resistant. It will grow very large leaves and send up shoots with small bell shaped flowers. You can trim leaves back several times a year and prevent the plant from flowering, causing it to continually build root mass instead. If you dig up the plant to propagate it you will often get another one or two regrowing in its place from the roots being cut when digging. If a plant can be eaten on by livestock, have leaves cut off of it, be chopped in half, regrow from pieces of root and still not only survive but regenerate I call that a pretty durable plant. Grass, especially burmuda grass is one thing that can end up choking it out. In polyculture environments this is less of concern than if you have a dedicated bed. Make sure to grass and weeds away from dedicated beds.